The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingComponents
...
Cleaning and protecting the vehicle interior
Perform cleaning in a manner
appropriate to each
component and its material.
Protecting the vehicle
interior
Remove dirt and dust using a
vacuum cleaner. Wipe dirty
surfaces with a cloth dampened
with lukewarm water.
If dirt cannot be removed,
wipe it off with a soft cloth
dampened with neut ...
Reassembly
Hint:
Use high-temperature grease to lubricate the bearings,
gears, return spring and steel ball when assembling the
starter.
Install planetary gear
Apply grease to the planetary gears and pin parts of
the planetary shaft.
Install the 3 planetary gears.
Install starter arm ...